PROJECT ABSTRACT A major gap in our knowledge is how best to intervene with children with autism spectrum disorder (ASD) who are progressing slowly in their speech production. By age 4, children who still only have a few functional words are very likely to remain minimally verbal by school age at 6-7 years. Currently nearly 30% of children with ASD are classified as minimally verbal (fewer than 20 functional words), and nearly 50% continue to have significant lags in their speech development1. Several factors likely play a role in speech delays including prelinguistic social communication skills (e.g., joint attention) and oral motor impairment 7,20,21. Social- communication skills, especially joint attention and requesting skills, are delayed in children with ASD, and have been linked to their later language development3,4. The JASPER (Joint Attention, Symbolic Play, Engagement & Regulation) intervention targets these skills specifically, and has shown improvement in joint attention, and later language8,11. However, for children with minimal speech skills at age 4, improving social-communication skills alone may not be enough to improve speech outcomes. An alternative and promising intervention focuses on the oral motor-sound system with direct prompting of speech. This intervention, PROMPT (Prompts for Restructuring Oral Muscular Phonetic Targets) is a multidimensional oral-motor approach to speech production disorders10. This intervention in combination with JASPER may have greater effect on speech outcomes than JASPER alone for 4 and 5 year- old children with ASD and minimal language production. Thus, the overarching goal of the proposed project is to determine whether there is additional benefit of adding an oral-motor intervention (PROMPT) to an evidence-based early intervention (JASPER) for speech outcomes. Specifically, the primary aim tests whether the combined intervention (JASPER + PROMPT) results in greater social communicative utterances (SCU) (primary outcome) than JASPER alone. SCUs are unprompted, generative (non-scripted) verbal utterances that are directed to a social partner for the purpose of sharing information (comment) or making a request. Secondary outcomes include intelligibility and number of novel words. Secondary aims focus on longitudinal outcome at kindergarten age, and which children might benefit the most from this novel intervention, including those with more joint attention or better oral motor development. Exploratory aims concern electrophysiological biomarkers of change with intervention and whether genetics play a role as a biological moderator of the effects of treatment. Child participants include 80 4-6 year-olds with ASD and limited language (<20 functional words). Children are randomized to JASPER or JASPER+PROMPT for a twice weekly intervention for 12 weeks, with 12 week follow up, and again one - year later. This study has the potential to dramatically improve communication outcomes for children with ASD, and addresses a high priority need of the Interagency Autism Coordinating Council and NIDCD.